Ourlong-termgoalistoprevent/treatacutekidneyinjury. Weareusingcisplatintoxicityasamodelofrenal injury, in vitro using cultured mouse kidney proximal tubule cells, and in vivo using wild-type and transgenic mice. We have established that inhibition of a cell cycle-associated enzyme,cyclin-dependentkinase-2 (Cdk2), protects from cytotoxicity in vitro and protects from kidney injury in vivo caused by cisplatin administration. Based on these findings, we developed two transgenic mouse strains resistant to cisplatin-induced acute renal injury because of specific cdk2 inhibition. We found that several pathways of cell death were dependent on Cdk2 activity and contribute to cisplatin cytotoxicity. Wefoundthatinresponsetocisplatin,Cdk2phosphorylatestwoproteins,p21andBcl-xL,thatdirectly and indirectly could have effects on cell death pathways. In our first specific aim we will investigate whether these phosphorylations have biologic effects on the proteins, and the mechanism of these effects. We hypothesized that Cdk2 inhibition is an effective strategy to prevent AKI. Our recently developed transgenic mice in which Cdk2 inhibitors can be induced in kidney tubules confirmed this hypothesis for cisplatin nephrotoxicity. In our second specific aim our transgenic mice will be used to determine whether Cdk2 inhibition will ameliorate other models of AKI, such as ischemia-reperfusion, nephrotoxic injury, or ER stress. We will determine whether the protein phosphorylations described above also occur in vivo, and using our transgenic mice, whether they correlate to the activation of kidney cell death pathways.